Closed tanks or receptacles storing fluids wherein fluids are periodically introduced into the tank, or removed therefrom, often utilize vents to prevent the buildup of pressure as the tank is being filled, and facilitate removal of liquid from the tank by preventing the formation of a vaccum.
It is an object of the invention to provide a closed tank for use with fuel tanks and the like, wherein the vent is of a large capacity, yet may be readily positioned as desired by gaseous pressure due to the counterbalancing of valve structure.
A further object of the invention is to provide a tank vent employing a gas operated valve wherein counterbalancing of the valve support structure permits the valve to be displaced to an egress vent position by the rise of gas pressure within the tank, and displaced to an ingress venting position by atmospheric pressure.
A further object of the invention is to provide a vent valve of large capacity for closed tanks wherein lock structure associated with the vent valve automatically locks upon tilting of the tank associated with the valve to prevent the inadvertent loss of liquid.
Yet another object of the invention is to provide a vent for closed tanks utilizing a counterbalanced valve wherein counterbalancing is produced by a pair of compression springs.
In the practice of the invention, the vent housing is mounted within an opening formed in the top of a closed tank, such as a fuel tank. The elongated body has a substantially vertical axis and an inner port communicates with the interior of the tank, and an exterior port is exposed to the atmosphere.
A valve is interposed between the inner and outer ports, and in its normal position, seals the inner port from the outer port to prevent evaporation of the confined liquid. The valve is mounted upon support structure movable along a substantially vertical axis and the weight of the support structure and valve is counterbalanced by a pair of compression springs. Counterbalancing of the valve permits the valve to be displaced to an egress venting position as the tank is being filled due to the exiting of gas therethrough. Conversely, during removal of the liquid within the tank, the resultant lowering of tank pressure permits the atmospheric pressure acting on the valve to displace the valve inwardly venting the tank during liquid withdrawal.
A gravity operated lock is mounted upon the valve support structure which prevents displacement of the valve from its normal closed position in the event of the tank tipping or tilting sufficiently to permit liquid loss through the vent sealing the inner and outer ports. The vent lock automatically realigns and activates itself upon the tank assuming its normal substantially vertical orientation.
The counterbalancing of the valve and valve support and the use of the lock permits the vent to have high capacity capabilities during both ingress and egress venting with safety.